2719

This number is a prime.

+ In 1917, Ramanujan gave a short list of odd numbers which cannot be written as x2 + y2 + 10z2. Eighty years later it is was shown that 2719 is surely the largest such number (GRH). Did you notice 2719 is a permutation of the Hardy-Ramanujan number? [Ono1997] [Beedassy]

(There is one curio for this number that has not yet been approved by an editor.)

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